Seroprevalence of brucellosis among animal handlers in West Bengal, India: an occupational health study.

Brucellosis is a highly contagious zoonotic disease and a major human health problem worldwide. Due to its ways of transmission, direct or indirect contact with infected animals or their contaminated biological products, the disease exhibits strong occupational association with animal handlers comprising a significant population at risk. This study was undertaken to estimate the seroprevalence of brucellosis in animal handlers and to understand the epidemiological and serological aspects of the same. The animal handlers from the state of West Bengal, India were included in this study. It was a prospective and observational cohort study from November 2021 to March 2022. A total of 669 sera samples were collected from animal handlers and tested using various serological tests for Brucella antibodies. All serum samples were tested using the Rose Bengal plate test (RBPT), standard tube agglutination test (STAT), and enzyme-linked immunosorbent assay (ELISA). 106 (15.8%) patients were diagnosed with brucellosis among the total number of patients tested. Most of the patients affected with brucellosis belonged to the age group 51-60 years (23.5%). The seropositivity rate in male animal handlers was higher than female animal handlers in this study. More studies are needed to understand the occupational association of this disease. Awareness programs, safe livestock practices, and prevention of the disease by timely diagnosis must be implemented in order to control human brucellosis.

Current Trends in Antimicrobial Resistance Patterns in Bacterial Pathogens among Adult and Pediatric Patients in the Intensive Care Unit in a Tertiary Care Hospital in Kolkata, India.

Nosocomial infections by multidrug-resistant (MDR) bacteria are among the main causes of morbidity and death in patients hospitalized in intensive care units (ICUs) worldwide. Antibiotic resistance has become a major concern for treating the patients with nosocomial infections. The aim of this study was to describe the antibiotic resistance patterns of pathogens causing infections in adult and pediatric patients in the ICUs of a tertiary care hospital in Kolkata, India. A cross-sectional, retrospective study was conducted from January 2022 to October 2022 on a total of 139 adult and 146 pediatric patients. Depending on clinical symptoms of the patients, samples were collected and subjected to antibiotic sensitivity testing. The culture and sensitivity pattern of clinical isolates from blood, urine, sputum, endotracheal tube (ET) aspirate, and central line catheter insertion site swabs were analyzed. A total of 695 and 556 specimens were obtained from adult and pediatric ICU, respectively. Culture positivity rate among adults and pediatric patients were 37% and 40%, respectively. The most commonly isolated organisms were Gram-negative Enterobacterales and non-fermenters. Most of the bacterial isolates showed very high resistance against multiple antibiotics. Escherichia coli from adult and pediatricpatients were found to be resistant to second generation cephalosporins (95% and 96%, respectively), beta-lactams (95% and 63%, respectively), fluoroquinolones (95% and 81%, respectively), and cotrimoxazole (85% and 78%, respectively). Klebsiella spp. from adult patients were found to be resistant to aminoglycosides (75%), second generation cephalosporins (100%), beta-lactams (94%), fluoroquinolones (92%), carbapenems (88%), and cotrimoxazole (83%). Proteus spp., Acinetobacter baumannii, and Pseudomonas spp. werefound to be resistant to multiple antibiotics. Enterococcus spp. from ICUs showed more than 90% resistance against ampicillin and more than 75% resistance against fluoroquinolones. MDR bacterial infections are increasing in both adult and pediatric ICUs, leading to significant therapeutic challenges. A frequent study of antimicrobial resistance patterns is imperative for antibiotic stewardshipin combatting the deadly effect of the MDR bacteria in critically ill patients.

Changing Paradigms in Antibiotic Resistance in Salmonella Species with Focus on Fluoroquinolone Resistance: A 5-Year Retrospective Study of Enteric Fever in a Tertiary Care Hospital in Kolkata, India.

Enteric fever, a potentially fatal multisystem disease that is caused by Salmonella enterica serovar Typhi and Paratyphi, poses a significant risk in low- and middle-income countries. A retrospective study to understand the prevalence and evolving patterns of antibiotic resistance in Salmonella Typhi and Paratyphi was undertaken from June 2017 to June 2022. A total of 4051 blood samples were collected from patients attending inpatient and outpatient departments of the School of Tropical Medicine (Kolkata, India) hospital. Blood samples were cultured, and culture positive samples were further processed for identification using conventional and automated systems. Antibiotic susceptibility test was performed using both the Kirby-Bauer disc diffusion method and VITEK2 (bioMerieux). Forty-five (1.1%) Salmonella species were isolated among the number of total (n = 4051) samples that were tested. Out of the 45 Salmonella isolates, 35 were Salmonella Typhi (77.77%) and 10 were Salmonella Paratyphi A (22.23%). We found pronounced fluoroquinolone resistance of 100% in the recent years (2019-2022) in both of the S. Typhi and S. Paratyphi A isolates. We found that 1 Salmonella Typhi and 2 Salmonella Paratyphi A isolates were resistant against multiple antibiotics (cefixime, ceftriaxone, ciprofloxacin and nalidixic acid), and 1 multidrug-resistant (MDR) Salmonella Paratyphi A isolate was found in a recent study year (2020) and it showed resistance against different classes of antibiotics (cephalosporins, fluoroquinolones and carbapenems). There was no resistance that was detected to the 3rd generation cephalosporins in the final years of the study. The emergence of Salmonella isolates that are resistant to multiple antibiotics poses a serious health problem. The antimicrobial resistance patterns that were detected in the study thus warrant further studies to understand the antibiotic susceptibility and resistance pattern of Salmonella against the major classes of antibiotics.

Changing Patterns of Salmonella enterica Serovar Rissen From Humans, Food Animals, and Animal-Derived Foods in China, 1995-2019.

Salmonellosis represents a growing threat to global public health. Salmonella enterica remains the leading cause of bacterial foodborne diseases in China. Salmonella enterica serovar Rissen (S. Rissen) has been recognized as one of the emerging serovars among humans in different countries worldwide. However, knowledge on the prevalence of S. Rissen in China is largely lacking. To address essential epidemiological information for S. Rissen in China, a total of 1,182 S. Rissen isolates recovered from samples across the food chain were collected from 16 provinces or province-level cities between 1995 and 2019. Risk factors due to the consumption of animal-derived food products were also analyzed. We found S. Rissen is widely distributed, especially in the Eastern and Southern parts of China, and there is an increasing frequency in recent years as evidenced by the greater number of isolates recovered in 2016, 2017, and 2018. Interestingly, the majority of S. Rissen isolates recovered in this study were from human samples (63.4%; 749/1182), remarkably, 58.4% (438/749) were from asymptomatic carriers. We obtained most of the S. Rissen isolates from humans from Guangxi (59.5%; 446/749) and Shanghai (29.5%; 221/749). Among 302 human diarrheal isolates (40.3%; 302/749), we found 44.6% (139/311) of S. Rissen in children with diarrhea (age below 10 years old). This is of clinical significance as diarrhea is one of the crucial causes of child mortality globally and our findings here highlighted the importance of Salmonella infections in Chinese children. Additionally, S. Rissen isolates were also found to be associated with pork and poultry products in China. This study projected the most updated national-wide study of S. Rissen isolates obtained from different sources in China over the past two decades. Continued surveillance is warranted to further monitor this emerging serovar in China and elsewhere over the world.

Characterization of Multidrug Resistance Patterns of Emerging Salmonella enterica Serovar Rissen along the Food Chain in China.

Salmonella spp. are recognized as important foodborne pathogens globally. Salmonella enterica serovar Rissen is one of the important Salmonella serovars linked with swine products in numerous countries and can transmit to humans by food chain contamination. Worldwide emerging S. Rissen is considered as one of the most common pathogens to cause human salmonellosis. The objective of this study was to determine the antimicrobial resistance properties and patterns of Salmonella Rissen isolates obtained from humans, animals, animal-derived food products, and the environment in China. Between 2016 and 2019, a total of 311 S. Rissen isolates from different provinces or province-level cities in China were included here. Bacterial isolates were characterized by serotyping and antimicrobial susceptibility testing. Minimum inhibitory concentration (MIC) values of 14 clinically relevant antimicrobials were obtained by broth microdilution method. S. Rissen isolates from humans were found dominant (67%; 208/311). S. Rissen isolates obtained from human patients were mostly found with diarrhea. Other S. Rissen isolates were acquired from food (22%; 69/311), animals (8%; 25/311), and the environment (3%; 9/311). Most of the isolates were resistant to tetracycline, trimethoprim-sulfamethoxazole, chloramphenicol, streptomycin, sulfisoxazole, and ampicillin. The S. Rissen isolates showed susceptibility against ceftriaxone, ceftiofur, gentamicin, nalidixic acid, ciprofloxacin, and azithromycin. In total, 92% of the S. Rissen isolates were multidrug-resistant and ASSuT (27%), ACT (25%), ACSSuT (22%), ACSSuTAmc (11%), and ACSSuTFox (7%) patterns were among the most prevalent antibiotic resistance patterns found in this study. The widespread dissemination of antimicrobial resistance could have emerged from misuse of antimicrobial agents in animal husbandry in China. These findings could be useful for rational antimicrobial usage against Salmonella Rissen infections.

Corrigendum: Antibiotic Resistance in Salmonella Typhimurium Isolates Recovered From the Food Chain Through National Antimicrobial Resistance Monitoring System Between 1996 and 2016.

[This corrects the article DOI: 10.3389/fmicb.2019.00985.].

Corrigendum: Genomic Characterization of mcr-1-carrying Salmonella enterica Serovar 4,[5],12:i:- ST 34 Clone Isolated From Pigs in China.

[This corrects the article DOI: 10.3389/fbioe.2020.00663.].

Genomic Characterization of mcr-1-carrying Salmonella enterica Serovar 4,[5],12:i:- ST 34 Clone Isolated From Pigs in China.

Salmonella enterica serovar 4,[5],12:i:-, so-called Typhimurium monophasic variant, has become one of the most frequently isolated serovars both in humans and in animals all over the world. The increasing prevalence of mcr-1-carrying Salmonella poses significant global health concerns. However, the potential role of Salmonella 4,[5],12:i:- in mcr-1 gene migration through the food chain to the human remains obscure. Here, we investigated 337 Salmonella isolates from apparently healthy finishing pigs, which is rarely studied, obtained from pig farms and slaughterhouses in China. The mcr-1 gene was found in four colistin-resistant S. enterica 4,[5],12:i:- isolates. Notably, all four isolates belonged to sequence type 34 (ST34) with multidrug resistance phenotype. Further genomic sequencing and antimicrobial resistance characterization confirmed that mcr was responsible for the colistin resistance, and the conjugation assay demonstrated that three of four isolates carried mcr-1 in IncHI2 plasmid. Importantly, mcr-1 and class-1 integron were found to co-localize in two strains with IncHI2 plasmid. By collecting all the mcr-1-carrying Typhimurium and monophasic variant strains across the food chain (farm animals, animal-origin food, and humans), our phylogenomic analysis of available 66 genomes, including four strains in this study, demonstrated an independent phylogenetic cluster of all eight Chinese swine-originated isolates and one human isolate. Together, this study provides direct evidence for clonal and pork-borne transmission of mcr-1 by Salmonella 4,[5],12:i:- ST34 in China and highlighted a domestication pathway by acquisition of additional antimicrobial resistance determinants in Chinese ST34 isolates.

Emerging colistin resistance in Salmonella enterica serovar Newport isolates from human infections.

Worldwide emergence of Salmonella enterica serovar Newport (S. Newport) infection in humans, in parallel with a significant increasing prevalence of antimicrobial resistance (AR), is a serious public health concern. However, the prevalence of S. Newport resistance in China remains largely unknown. A retrospective study of 287 S. Newport clinical isolates collected during 1997-2018 was undertaken for characterization of AR profiles using the micro-dilution assay. We found a recent emergence of colistin resistance in four Chinese clinical isolates, including mcr-1-positive isolates. Importantly, phylogenomic and microbiological investigations indicate multiple independent clonal transmission of colistin-resistant S. Newport isolates of different seafood origins. Our study highlights potential reservoirs for transmission of colistin resistance and suggests that the global food supply chain may facilitate this dissemination.

Genomic Characterization of New Variant of Hydrogen Sulfide (H2S)-Producing Escherichia coli with Multidrug Resistance Properties Carrying the mcr-1 Gene in China †.

Colistin is considered to be a 'last-resort' antimicrobial for the treatment of multidrug-resistant Gram-negative bacterial infections. Identification of Enterobacteriaceae, carrying the transferable colistin resistance gene mcr-1, has recently provoked a global health concern. This report presents the first detection of a hydrogen sulfide (H2S)-producing Escherichia coli variant isolated from a human in China, with multidrug resistance (MDR) properties, including colistin resistance by the mcr-1 gene, which could have great implications for the treatment of human infections.

Emergence and Dissemination of mcr-Carrying Clinically Relevant Salmonella Typhimurium Monophasic Clone ST34.

Antibiotic resistance in bacteria is one of the urgent threats to both public and global health. The Salmonella Typhimurium monophasic sequence type 34 (ST34) clone, with its rapid dissemination and resistance to numerous critical antimicrobials, has raised global concerns. Here, we present an updated overview on the emerging infections caused by mobile colistin resistance (mcr)-carrying colistin-resistant ST34 isolates, covering their global dissemination and virulence-associated efficacy. The higher rates of mcr-1-positive ST34 in children in China highlights the increasing threat caused by this pathogen. Most of the ST34 isolates carrying the mcr-1 gene were isolated from animals and food products, indicating the role of foodborne transmission of mcr-1. The emergence of multidrug resistance genes along with various virulence factors and many heavy metal resistance genes on the chromosome and plasmid from ST34 isolates will challenge available therapeutic options. The presence of the colistin resistance gene (mcr-1, mcr-3, and mcr-5) with the multidrug-resistant phenotype in ST34 has spread across different countries, and most of the mcr-1 genes in ST34 isolates were detected in plasmid type IncHI2 followed by IncI2, and IncX4. Together, mcr-carrying S. Typhimurium ST34 may become a new pandemic clone. The fast detection and active surveillance in community, hospital, animal herds, food products and environment are urgently warranted.

Antibiotic Resistance in Salmonella Typhimurium Isolates Recovered From the Food Chain Through National Antimicrobial Resistance Monitoring System Between 1996 and 2016.

Salmonella is a major foodborne pathogen which causes widespread contamination and infection worldwide. Salmonella Typhimurium is one of the leading serovars responsible for human and animal salmonellosis, globally. The increasing rate of antibiotic resistance in Salmonella Typhimurium poses a significant global concern, and an improved understanding of the distribution of antibiotic resistance patterns in Salmonella Typhimurium is essential for choosing the suitable antibiotic for the treatment of infections. To evaluate the roles of animal and human in antibiotic resistance dissemination, this study aims to categorize 11,447 S. Typhimurium strains obtained across the food-chain, including food animals, retail meats and humans for 21 years in the United States by analyzing minimum inhibitory concentrations (MICs) values for 27 antibiotics. Random Forest Algorithm and Hierarchical Clustering statistics were used to group the strains according to their minimum inhibitory concentration values. Classification and Regression Tree analysis was used to identify the best classifier for human- and animal-populations' isolates. We found the persistent population or multi-drug resistant strains of S. Typhimurium across the four time periods (1996∼2000, 2001∼2005, 2006∼2010, 2011∼2016). Importantly, we also detected that there was more diversity in the MIC patterns among S. Typhimurium strains isolated between 2011 and 2016, which suggests significant emergence of diversified multi-drug resistant strains. The most frequently observed (43%) antibiotic resistance patterns found in S. Typhimurium were tetra-resistant pattern ASSuT (ampicillin, streptomycin, sulfonamides, and tetracycline) and the penta-resistant pattern ACSSuT (ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline). Animals (mainly swine and bovine) are the major source for these two frequently found antibiotic resistance patterns. The occurrence of antibiotic resistant strains from humans and chicken is alarming. Strains were mostly susceptible to fluoroquinolones. Together, this study helped in understanding the expansion of dynamics of antibiotic resistance of S. Typhimurium and recommended fluoroquinolones as a possible treatment options against S. Typhimurium infection.

Antimicrobial Susceptibility of Enteric Gram Negative Facultative Anaerobe Bacilli in Aerobic versus Anaerobic Conditions.

Antimicrobial treatments result in the host's enteric bacteria being exposed to the antimicrobials. Pharmacodynamic models can describe how this exposure affects the enteric bacteria and their antimicrobial resistance. The models utilize measurements of bacterial antimicrobial susceptibility traditionally obtained in vitro in aerobic conditions. However, in vivo enteric bacteria are exposed to antimicrobials in anaerobic conditions of the lower intestine. Some of enteric bacteria of food animals are potential foodborne pathogens, e.g., Gram-negative bacilli Escherichia coli and Salmonella enterica. These are facultative anaerobes; their physiology and growth rates change in anaerobic conditions. We hypothesized that their antimicrobial susceptibility also changes, and evaluated differences in the susceptibility in aerobic vs. anaerobic conditions of generic E. coli and Salmonella enterica of diverse serovars isolated from cattle feces. Susceptibility of an isolate was evaluated as its minimum inhibitory concentration (MIC) measured by E-Test® following 24 hours of adaptation to the conditions on Mueller-Hinton agar, and on a more complex tryptic soy agar with 5% sheep blood (BAP) media. We considered all major antimicrobial drug classes used in the U.S. to treat cattle: ß-lactams (specifically, ampicillin and ceftriaxone E-Test®), aminoglycosides (gentamicin and kanamycin), fluoroquinolones (enrofloxacin), classical macrolides (erythromycin), azalides (azithromycin), sulfanomides (sulfamethoxazole/trimethoprim), and tetracyclines (tetracycline). Statistical analyses were conducted for the isolates (n≥30) interpreted as susceptible to the antimicrobials based on the clinical breakpoint interpretation for human infection. Bacterial susceptibility to every antimicrobial tested was statistically significantly different in anaerobic vs. aerobic conditions on both media, except for no difference in susceptibility to ceftriaxone on BAP agar. A satellite experiment suggested that during first days in anaerobic conditions the susceptibility changes with time. The results demonstrate that assessing effects of antimicrobial treatments on resistance in the host's enteric bacteria that are Gram negative facultative Anaerobe Bacilli requires data on the bacterial antimicrobial susceptibility in the conditions resembling those in the intestine.

Synthetic aminoglycosides efficiently suppress cystic fibrosis transmembrane conductance regulator nonsense mutations and are enhanced by ivacaftor.

New drugs are needed to enhance premature termination codon (PTC) suppression to treat the underlying cause of cystic fibrosis (CF) and other diseases caused by nonsense mutations. We tested new synthetic aminoglycoside derivatives expressly developed for PTC suppression in a series of complementary CF models. Using a dual-luciferase reporter system containing the four most prevalent CF transmembrane conductance regulator (CFTR) nonsense mutations (G542X, R553X, R1162X, and W1282X) within their local sequence contexts (the three codons on either side of the PTC), we found that NB124 promoted the most readthrough of G542X, R1162X, and W1282X PTCs. NB124 also restored full-length CFTR expression and chloride transport in Fischer rat thyroid cells stably transduced with a CFTR-G542XcDNA transgene, and was superior to gentamicin and other aminoglycosides tested. NB124 restored CFTR function to roughly 7% of wild-type activity in primary human bronchial epithelial (HBE) CF cells (G542X/delF508), a highly relevant preclinical model with endogenous CFTR expression. Efficacy was further enhanced by addition of the CFTR potentiator, ivacaftor (VX-770), to airway cells expressing CFTR PTCs. NB124 treatment rescued CFTR function in a CF mouse model expressing a human CFTR-G542X transgene; efficacy was superior to gentamicin and exhibited favorable pharmacokinetic properties, suggesting that in vitro results translated to clinical benefit in vivo. NB124 was also less cytotoxic than gentamicin in a tissue-based model for ototoxicity. These results provide evidence that NB124 and other synthetic aminoglycosides provide a 10-fold improvement in therapeutic index over gentamicin and other first-generation aminoglycosides, providing a promising treatment for a wide array of CFTR nonsense mutations.

Use of MALDI-TOF mass spectrometry for identification of bacteria that are difficult to culture.

Rapid and reliable detection and identification of bacterial species are necessary for diagnosis and efficient treatment. Until recently, bacterial identification in clinical laboratories has mainly relied on conventional phenotypic and gene sequencing identification techniques. The identification of anaerobic bacteria, fastidious and slow growing bacteria using conventional methods is time consuming, expensive and complicated. Many anaerobes grow poorly or are nonreactive in most diagnostic systems. Unambiguous diagnosis of active tuberculosis is a time-consuming process, requiring as long as 12 weeks for positive identification of the organism. This long time frame presents challenges for case identification. Early identification of pathogenic bacteria is very important for the disease control. Recently, bacteriologists have focused their attention on the use of mass spectrometry (MS) for bacterial identification, especially Matrix Assisted Laser Desorption Ionization Time-Of-Flight (MALDI-TOF). Use of MALDI-TOF-MS is described in this review, with a special emphasis on the successful identification of groups of bacteria, which are difficult to culture. MALDI-TOF-MS is a powerful, rapid, precise, and cost-effective method for identification of intact bacteria, compared to conventional phenotypic techniques or molecular biology. Our review suggests that identification of anaerobes, fastidious bacteria and slow growing bacteria, has been improved by the arrival of MALDI-TOF-MS in clinical laboratories.

Colistin: an update on the antibiotic of the 21st century.

The emergence of multidrug-resistant Gram-negative bacteria that cause nosocomial infections is a growing problem worldwide. Colistin was first introduced in 1952 and was used until the early 1980s for the treatment of infections caused by Gram-negative bacilli. In vitro, colistin has demonstrated excellent activity against various Gram-negative rod-shaped bacteria, including multidrug-resistant Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae. Recent clinical findings regarding colistin activity, pharmacokinetic properties, clinical uses, emerging resistance, toxicities and combination therapy have been reviewed. Recent approaches to the use of colistin in combination with other antibiotics hold promise for increased antibacterial efficacy. It is probable that colistin will be the 'last-line' therapeutic drug against multidrug-resistant Gram-negative pathogens in the 21st century.

Bartonella infection: treatment and drug resistance.

Bartonella species, which belong to the α-2 subgroup of Proteobacteria, are fastidious Gram-negative bacteria that are highly adapted to their mammalian host reservoirs. Bartonella species are responsible for different clinical conditions affecting humans, including Carrion's disease, cat scratch disease, trench fever, bacillary angiomatosis, endocarditis and peliosis hepatis. While some of these diseases can resolve spontaneously without treatment, in other cases, the disease is fatal without antibiotic treatment. In this article, we discuss the antibiotic susceptibility patterns of Bartonella species, detected using several methods. We also provide an overview of Bartonella infection in humans and animals and discuss the antibiotic treatment recommendations for the different infections, treatment failure and the molecular mechanism of antibiotic resistance in these bacteria.